KF2 Configuration
 

With the latest generation of cars like the YZ-2, XB2 and B6 running a lot more mid weight and a lighter rear end than previously. I wondered if anyone had tried a slightly different configuration in their KF2?

Rather than running the low grip set-up, I'm considering moving the motor 20mm further forward, then putting a shorty lipo in the forward position in the space where you'd put saddles? This way you'll get a bit more weight around the mid and take some away from the rear.

Thoughts?

ben jemmo runs kf2 kit motor position, and stubby where saddle is, details on petite rc

You got a link? Can't seem to find it!

Interesting- i wonder what length belt? I can't see any further detail from the pictures.

Edit;
DOH! 117T clear as day...

I run the motor in kit position with a shorty lipo but use the Schumacher K2 battery straps so you can have the battery back or forward here's Bens from Petit site

http://site.petitrc.com/setup/schuma...n_RHR20150322/

I plan on doing the same Paul rather than the shorty being fixed in place, I'm most inclined to try the shorty in the forward position!

My dad has also been experimenting around with removing plates from the slipper assembly in certain conditions, this could work quite well with this 117t belt set-up if you want more of a 4-gear action in slippy conditions instead of the '3.5-gear' feel.

For those after the 117t, part number is U4494 :)

Even with the low grip layout the weight is a long way forwards, not to say there isn't an advantage to putting the motor all the way forwards if the grip on the track is there. I was thinking of trying motor forwards, but shorty at the back on astro.

I've already been running 40g infront of the motor for the last little while, so makes sense for me to try the motor forward by 20mm.

The latest generation of cars are incredibly light weight on the rear end, but they seem to get round this by mounting the shock much further in on the rear tower so I may try adding a new hole!

Putting the rear shocks forwards and running an LCG LiPo are also options for moving the weight forwards.

Ready to test at Mendip RC Raceway tomorrow evening!

Motor moved 20mm further forward as per kit (non low grip conversion), shorty in the forward position, rear shock tower redrilled to move the shocks further in as an option. Just waiting for the 117t belt to arrive tomorrow :)

http://i.imgur.com/fMecpHc.jpg

http://www.racing-cars.com/pp/New_Ca...KF2/U4403.html


http://www.racing-cars.com/images/u4403_w.jpg

They're coming with the belt tomorrow :thumbsup:

Looks good Dan, are you going to try LiPo forwards and backwards?

I just plan on running it in the forward position and adapting the set-up to suit. Last night we tried it at Mendip RC Raceway's bumpy, high-grip astro track and it went great! A few changes were needed to get it there though :)

Extra hole inwards on the rear tower
We drilled in extra hole inwards on the rear tower, a lot of the 3-gear cars have the shocks a lot more led down so we thought we would try the same. Works good with this new layout and the bumps on the track just vanished!

All slipper pad weights removed except a standard dual set-up
The slipper assembly works great on the low grip layout, but not so much with this new layout! With the extra forward weight AND the large slipper assembly the car was pitching forward too much. We removed all the pads except 2x like on a standard slipper set-up and used a 5mm bearing as a spacer where the spring sits to help pinch up the new set-up. Removing all the pads stops the car pitching around as much and keeps it much more neutral, was skimming over the bumps with ease now!

Shorty weight under lipo
I tried a few different weights under the lipo as well. 35g under the lipo tamed the car down which was nice to drive but a little lively. 70g took too much steering away and caused the rear to lean a little too much. I'll probably end up switching between 35/50g under the lipo depending on what I want the car to do.

+50cst/2.5wt in front shocks
With the weight being that much further forward, the car was diving quite a lot off power and actually causing the rear inside wheel to nearly lift and the geared diff to diff out! I'd suggest if you try this forward layout, you need to add +50cst weight in your front shocks to compensate :)

Overall though the car was real good, and probably the best my KF2 has felt! I'll be running this same set-up in the wet too, will just need a few tweaks.

Thanks for the feedback Dan, top stuff.

For the past two years, I've settled on running the KF with kit motor position (and running the shocks on the front of the rear wishbone), but running saddles, with longest wheelbase. The car has a much better balance, and rides the bumps a lot better. We run some fairly bumpy regionals here in the NE, and I've very happy with the way the car glides around the track now.

My thoughts were that the rear of the car was over rotating on power in other configurations, so reducing the weight in the rear of the car, reduced the momentum of the rear of the car rotating.

I played around with moving shocks from the front to the rear, but though I couldn't find a happy medium, I preferred them on the front of the wishbone, and this reduced the over rotation, and gave more steering. Last night I went to small bore rear shocks, mounted on the front of the wishbone, and this was the best it had felt.

Im on 550 front oil black springs, 350 rear oil red springs (small bore).

I also found running the front wishbones on long wheelbase, meant the front wasn't pitching in too much with the weight further forward.

The setup seems to work well on astro, grass, carpet, and multi surface.

I'm going to fit the 117T belt , and try a shorty fwd like yourself, maybe this will be going too far with moving weight fwd, considering my shock position?

I hadn't thought of leaning the rear shocks in further, I might give that a go aswell.

Thanks again for the feedback, Chris.

Thanks for posting Dan.

What rear springs and lower shock position were you running?

What were you thinking for the wet?

Cheers

I'll reply as I've been running this setup with Dan ..

We have been using mostly kit setup all round, so red rear springs on middle wishbone hole, with 3 x 1.7 pistons on 400cst oil ... and seems to work quite well on bumpy high grip astro.

Moving the shocks in on a new hole in the tower loosens the back up in the turns more than kit, doesn't feel so locked in .. takes a while to get used to but seems to work with the lower rear weight bias.

Taking the slipper plates out seems a really good tuning option with this layout too .. stock slipper has quite a forward kick on power ..

Do you think running motor forward causes a problem of the rear being too locked in though? Just wondering why you are looking to free the back end up with laid down shocks when moving weight forward, I would have thought, and have experienced the opposite to be true .... where moving the weight forward has increased steering, and so no need to free up the rear. But....... consider, my shocks are on the front of the rear wishbone.

It's hard to say really. Its a setup we thought up to try and get the KF to work more like the YZ2 and B6/B5m laydown ... they just seem to drive round our track (Mendip) like they're on rails ... and better over the bumps by miles !!

A more central weight gives more natural stability, moving the shocks in on the tower makes the suspension softer and more progressive and adds back in the traction plus steering .. it definitely has a good feel about it ..

All I can say is try it ... its an easy conversion ..

Thanks, will try it this weekend.

Cool .. let us know how you get on :thumbsup:

So, with the revised layout, I attended NEAM at Seaham on Sunday night. Its a all carpet with typical indoor features. On the flat, the car was very good, very sharp, without over rotating. A bit more lively than with the saddles in.
But we had some overlapped gym mats, and small moguls, which the back of the car was skipping about on too much.
I moved the shorty position further back, to stop the back skipping up too much, and this worked well.
I ran like this for the final few runs of the night, very happy with the cars pace ..... rapido.

I can't help but feel, that it'll be quicker with the shorty further forward though, if I can manage to somehow keep the rear in check over the bumps.

Sounds like you liked the layout :thumbsup:

Did you try with a new hole drilled in the shock mount ? .. and did you run stock slipper or the stripped down version ?

Hi,
I used a lightweight slipper assembly. I had the shocks drilled around 12mm inboard of the existing inboard hole. See the picture attached.

Could also use the alloy side rails and loose the top deck.

*slight tangent*
Alloy stiffeners or carbon top deck? Which one and why? I'm just about to get the MM carbon chassis and could do with a bit of a point in the right direction! I'll be swapping between carpet/astro and dirt configurations.

Hi Mark, good idea, but this car is a KF1, so there isn't an option of alloy side rails.
Chris.

There is u4892 fits as I have them on my kf1 so it looks like the one Ben is running.....

KF1 with alloy stiffeners


https://scontent-lhr3-1.xx.fbcdn.net...68945818_o.jpg

Thanks Mark, I'll give it a try.

Cars been going really well in this configuration, definitely won't be going back to the other layout! Been experimenting with 30-50g weight under the lipo in different conditions.

12mm seems a long way to drill the rear shock position! We've drilled ours about 6mm further in and has been working well.

I would definitely recommend this layout, moving the rear shocks 6mm further in on the rear tower, removing the weight from the slipper and 30-50g under the lipo :)

what chassis are you using alloy or carbon?

Alloy ..

Try going for larger shock piston holes and up the shock oil wt. to compensate.

Sure laying the shocks over changes the rising rate a bit but mainly it's just making it softer. Easy option is just to use a softer spring. What's the weight distribution with the lipo forward and wonder how this compares with B6?

Hi Dan/ Si,

Can you upload a photo of the rear shock tower pick ups?

I'm currently running my KF2 SE in mid conversion , this is different to your layout I know; however, I also have two extra inner holes on my rear tower. I find this works very well on low grip or blow out grass with 30-40g under a shorty or 80g under a LG lipo . Would be nice to get a comparison

are you running any rear weight with mid on grass? I find the weight too far forwards and wouldn't add anything under the LiPo in mid layout.

Sorry mate don't have a pic but the holes are in line with the existing ones, about 6mm in, and 69mm between centres, Works a treat ...

Ran mine for the first time properly on Sunday at the South West regional at Tiverton, sandy astro with bumpy and cut up grass sections.

I haven't gone well there for a few years now, never have enough steering or traction with the KF2 before ..

Wasn't a problem this time, had kit setup, apart from 1.7 x 3 rear pistons on 400 cst oil. All kit geometry, and diff.

Ran the car with the new forward weight, and stripped down slipper, 50gms under the lipo, staggers up front and yellow mini spike out back.

The car drove a dream !!!! tonnes of steering and enough traction .. even on the sandy bits !! Only change I made all day was to widen the rear track 3mm overall to gain a little turn in off power, and a little more on power traction ..

Gave me my best result for ages ... 2nd in the B final and hunting down 1st place .. just needed one more lap lol ...

Yes mate . 40g under the belt and 10g on the rear of the shock tower.

Hi guys, a question if I may. I ran my KF2 SE for the first time today on a small very bumpy mixed astro track. It seemed to go pretty well, apart from a small steering assembly mishap...
At the moment I only have saddle packs, so I had to run it in the forward motor position. Having read this thread and not having tried anything else yet, how does my layout work compared to the low grip motor position and a shorty? I have the bits to run it forward motor and shorty like you guys apart from the 117 tooth belt, but at the moment I feel a little bit more weight on the rear would settle it down more, thats why I am thinking try low grip first. I have the shocks on the rear and a ball diff, the rear seemed fairly well planted but did break loose occasionally.
Cheers :)